What kind of time demand can I expect from National Guard Special Forces?

I am planning on joining the National Guard through an 18x contract this year. I am 31, in North Carolina, self employed, and have two young children and a wife. I have always wanted to serve my country in my highest capacity, and the National Guard SEEMED to be a way to serve and still have time for family. I understand the training to become special forces is a timeline of over 2+ years. My main question is-after joining the 20th special forces unit in SC or WV, how much time on average would the unit require from me? The national guard makes it sound like it's one weekend a month and three weeks a year in the summer. I've heard others say its three to four weekends a month with long training once a year. I need to gather all the information I can before making a decision that is best for my family. I will more than likely go 11B for primary MOS, but I want more for myself ultimately. Any advice is very appreciated especially by those who have been in the guard. Thank you all.